The invention relates to an apparatus for underground tunneling, especially for tunnels of unwalkable cross section, containing: a working tube having an axis, which can be urged forward in the direction of the tunnel in formation, a digging unit which is mounted in the working tube and can be pushed past the front end of the working tube, and which is movable radially of its axis and bears a partial-face cutter for loosening the dirt in front of the working tube and can be set for a substantially smaller outside cross section in comparison to the inside cross section of the working tube, and a carrier system for the removal of the dirt loosened in the driving of the tunnel.
In apparatus of this kind it is known (DE-OS No. 34 23 842) to transport the dirt from the working face back to the starting pit by means of a shovel powered by chains, or a conveyor belt, or a pusher system. The use of such conveyor means is possible because the digging unit has a digging tool in the form of a swiveling ball cutter and therefore it can be set to cut on a substantially smaller cross section than the full interior cross section of the working tube. Such conveyor systems, however, have the disadvantage that as the tunnel bore becomes gradually longer, they have to be lengthened accordingly. In digging very long tunnels of a length of more than 100 meters, for example, this entails a great expenditure of time and material. The same deficiency is encountered in the use of chain conveyors or the like (DE-AS 19 13 182, U.S. Pat. No. 4,232,905) which are known in apparatus that operate in a similar manner. Aside from these, the described conveyor systems, when used in the digging of unwalkable cross sections, i.e., those of 1000 mm diameter or less, are hard to handle on account of the cramped available space, involve many imponderables, and are very much subject to breakdowns. It is furthermore difficult to withdraw them from the work face back to the starting pit for repairs and maintenance and reinstall them at the work face. Lastly, these conveyor systems are subject to severe mechanical wear, so that they often quickly become unusable, since at least those parts that cannot be retrieved from the tunnel can neither be maintained nor repaired in case of necessity.
In underground tunneling by means of digging units which have an outside cross section of substantially the inside diameter of the working tube and a digging tool in the form of a full-face cutterhead, therefore, a flushing liquid is always used for the removal of the dirt (DE-OS 32 04 564). Such systems often cannot be used, however, on account of the hardly avoidable seepage and infiltration of the flushing liquid in the ground, and require troublesome and costly storage and processing equipment to handle the flushing liquid. Also, it is not possible to remove large stones or rock fragments with such systems.
It is the object of the invention to improve the apparatus of the kind described above in such a manner that a trouble-free, long-wearing system will result, which can be retrieved from the tunnel by simple means, whose lengthening requires simple components or none at all, and which therefore can be manufactured at low cost and will be very quick and easy to use.